hera_sim.noise.ThermalNoise¶
- class hera_sim.noise.ThermalNoise(Tsky_mdl=None, omega_p=None, integration_time=None, channel_width=None, Trx=0, autovis=None, antpair=None, rng=None)[source]¶
Generate thermal noise based on a sky model.
- Parameters:
Tsky_mdl (callable, optional) – A function of
(lsts, freq)
that returns the integrated sky temperature at that time/frequency. If not provided, assumes a power-law temperature with 180 K at 180 MHz and spectral index of -2.5.omega_p (array_like or callable, optional) – If callable, a function of frequency giving the integrated beam area. If an array, same length as given frequencies.
integration_time (float, optional) – Integration time in seconds. By default, use the average difference between given LSTs.
channel_width (float, optional) – Channel width in Hz, by default the mean difference between frequencies.
Trx (float, optional) – Receiver temperature in K
autovis (float, optional) – Autocorrelation visibility amplitude. Used if provided instead of
Tsky_mdl
.antpair (tuple of int, optional) – Antenna numbers for the baseline that noise is being simulated for. This is just used to determine whether to simulate noise via the radiometer equation or to just add a bias from the receiver temperature.
rng (np.random.Generator, optional) – Random number generator.
Notes
Considering the SNR in autocorrelations is typically very high, we only add a receiver temperature bias to the autocorrelations.
Methods
__call__
(lsts, freqs, **kwargs)Compute the thermal noise.
Get all the aliases by which this model can be identified.
get_model
(mdl)Get a model with a particular name (including aliases).
get_models
([with_aliases])Get a dictionary of models associated with this component.
resample_Tsky
(lsts, freqs[, Tsky_mdl, Tsky, ...])Evaluate an array of sky temperatures.
Attributes
Mapping between parameter names and Simulator attributes
Whether this systematic multiplies existing visibilities
Whether this systematic contains a randomized component
Whether the returned value is per-antenna, per-baseline, or the full array